This invention relates to an intermediate adapter used to couple interchangeable lenses and camera bodies of different flange focal distances (distance between the flange surface and focal phase), thus permitting the use of an interchangeable lens of large flange focal distance with a camera body having a small flange focal distance.
For instance, when it is required to use an interchangeable lens originally intended for use with a single-lens reflex camera having a larger flange focal distance and image size with a video camera, it is necessary to compensate for the difference in flange focal distance by mounting an intermediate adapter therebetween. However, a conventional intermediate adapter does not allow the correlative operation of the interchangeable lens and the video camera body. Accordingly, heretofore it has been impossible to perform a motion picture photographing operation in an automatic aperture control mode in such a situation, and it is also impossible to use the interchangeable lens in an automatic aperture control mode even for still picture photographing operation. In other words, it is impossible to continuously operate (adjust the amount of opening of) the aperture according to the brightness of the object, and it is also impossible to carry out a preset automatic aperture control operation in which the aperture is normally fully opened and decreased to an aperture value used only in a still picture photographing operation.